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By Toivo Toivanen

The paper begins with a brief history of the nickel industry in Finland, and then deals with the introduction of the flash smelting process. The main part of the paper is devoted to nickel refining, which is studied under four main headings -grinding, leaching, electrolyte precipitation, and nickel electrowinning. Flowsheets are illustrated, and the equipment used is described. Analyses of the material in the various stages, from concentrate to high-grade nickel matte, are also presented. N ICKEL made its appearance in the Finnish mining industry forty years ago, when a nickel deposit was discovered at Petsamo in Lapland. Mond Nickel Co. received the concession for this deposit from the Finnish Government, and the Petsamon Nikkeli Company constructed a mine and a nickel smelter (1), the completion of which was prevented by the 1939 Winter War. The mine and smelter were, however, completed soon afterwards in spite of World War II,

Jan 1, 1964

By G. R. Speich, L. Zwell, H. A. Wriedt

HORNBOGEN1 has recently shown that it is possible to measure the degree of segregation accompanying cellular precipitation in ferritic Fe-Zn alloys by measuring the lattice parameter of the ferrite phase within the cell. In extending this work to study a wider range of composition and to evaluate the free-energy change accompanying the growth of the cells, the lattice parameter and the boundary of the a! phase in Fe-Zn alloys were redetermined to check the earlier work of Schramm.2 This appeared to be necessary since the Fe-Zn diagram has been drastically revised since the work of Schramm. Stadelmaier and Bridgers3 have recently shown that, contrary to prior belief: the y iron field is closed and the a phase boundary extends to an a + T + L peritectic at 782°C where peritectic a contains 42 at, pet Zn. The phase T in equilibrium with the a solid solution has a composition near Fe3Zn10 and a cubic 081 type structure.' The alloys were prepared by two different methods. In the first method carbonyl iron powder (400 mesh, 99.8 pet pure) and high-purity zinc powder (200 mesh, 99.99 pet pure) were mixed in a ball mill and then pressed in a die at 40,000 psi pressure to make compacts with a diameter of 5/8 in. and a thickness of l/4 in. These were sealed in evacuated quartz capsules, gradually heated to 1100°C over a period of 1 week (3 days at 600°C) 3 days at 800°C, 1 day at (1100°C), and then quenched in iced brine. For the alloys containing 23.4 and 30.1 at. pet Zn, the final homogenization anneals were performed at 1000" and 850°C) respectively, to prevent melting. In the second method, alloys were prepared by saturating high-purity iron millings (0.001 in. thick, 99.9 pet pure) in zinc vapor. For each alloy the impregnation was conducted at a fixed vapor pressure of zinc and a fixed temperature between 750' and 800°C. When saturated, the millings were quenched in water. The compositions of the alloys prepared by both methods are shown in Table I. The lattice parameters of the ferritic solid solutions were determined by comparing the 26 values of their 310, peaks (using Co Ka) or of their 211 , peaks (using Cr Ka) with those of corresponding peaks for high-purity a iron. The 20 values were measured at room temperature with an X-ray dif-fractometer (G.E.-XRD5). By using a fiducial value of 2.8664Å for the lattice parameter of pure a iron at 25oC,5 the lattice parameters of the zinc-bearing

Jan 1, 1964

By A Palynchuk

The development of welded pipe has paralleled the general industrial development and, in particular, that of the petroleum industry. The petroleum industry's need for high-grade, economical pipeline material to make many 'of its projects feasible has been a significant factor in the development of light-wall, high-grade welded pipe. The modern welding processes, such as high-frequency, electric resistance, flash, submerged arc, etc., have some basically different characteristics. The modern high-frequency weld mill is a complex of specialized equipment that is integrated into a production unit. Each component in the unit performs a specific function in the production process. Quality control must be built into the process on an operating basis and, to maintain the quality required for pipeline standards, must be more than a policing operation. The further development of the welded pipe industry will be determined by changing and increasing demands. The technical and economic views and requirements that will influence the development have to be resolved.

Jan 1, 1964

By Murray Udy

La Corporación Venezolana de Guayana ( CVG) decidió renovar su noveno horno eléctrico de reducción a través de un nuevo proceso para la fabricación del fierro Strategic-Ud. En este sentido, el presente artículo señala la la instalación de este nuevo proceso de producción de hierro en la planta siderúrgica del Orinoco. La implantación del Strategic-Udy se inició en 1963 y es una combinación de operaciones unitarias conocidas con una técnica operativa mejorada, a fin de ofrecer mejor control sobre los procesos químicos e incrementar la eficiencia de la técnica antigua. Asimismo este nuevo proceso, elimina las limitaciones de tamaño y calidad del material impuestas en los procesos existentes para la fabricación del fierro.

Jan 1, 1964

By John Chipman, Wayne L. Worrell

Using recent thermodynamic data for the carbides and oxides of tantalum, columbium, and vanadium, the stable solid phases aboue 1300°K and at 1 atm CO(g) pressure in each M-C-O system have been determined. Pourbaix-Ellingham diagrams have been constructed and are used to estimate the minimum temperatures necessary to obtain these metals by carbothermic reduction under reduced pressures. TANTALUM, columbium, and vanadium react with carbon to form the M,C and MC carbide phases. The M,C carbides have narrow homogeneity ranges, but the MC phases possess considerable ranges of homogeneity.' The free energies of formation of the MC carbides were recently measured, and those of MC and M2Ccarbides have been estimated., (The notations MC and MC denote, respectively, the carbide compositions at the carbon-rich and at the metal-rich boundaries of the homogeneous MC phase.) In this paper, these carbide data are combined with thermodynamic data for the oxides to predict the stable phases in the Ta-C-O, Cb-C-O, and V-C-O systems at specified temperatures and oxygen pressures. M-C-O PHASE DIAGRAMS The solid phases in equilibrium above 1300°K for each M-C-0 system are shown in Figs. 1, 2, and 3. Above 1300°K, the vapor would consist entirely of carbon monoxide; and these phase diagrams were obtained by specifying the vapor pressure of CO(g) to be 1 atm. The temperature at which any two solid phases become unstable is specified along the two-phase equilibrium lines in each diagram. To simplify the diagrams, all solid phases in the Ta-C-O and Cb-C-O systems are represented as stoichiometric compounds. However, the homogeneity ranges of VO and VC are indicated, because they form a complete series of solid solutions.3 It also should be noted that the homogeneity range of

Jan 1, 1964

By F J. Pearce

The Steel Company of Canada, utilizing the S-L process, has produced partially and highly reduced pellets for use in the blast furnace. Experimental blast furnace tests, using reduced pellet burdens, have been carried out. The changes in production rate, fuel rate and general performance of both the S-L and the blast furnace processes are indicated. Introduction T HE ore burdens for a blast furnace may be improved in two ways: chemically, by concentrating the ore to a high degree of purity; and physically, by agglomerating or closely sizing the ore particles. Today, many b1ast furnaces are charged with closely sized agglomerates, some of which contain upwards of 66 per cent iron. The further improvement of these burdens by chemical concentration may, in many instances, be uneconomic due to the large losses of iron that occur during processing. Assuming that it would be possible to reject all of the gangue minerals, the maximum level of concentration of iron in the hematitic ores would be only about 70 per cent.

Jan 1, 1964

The widely accepted kinetic model for the gaseous reduction of hematite is critically examined. The formation of the wustite layer during internal reduction cannot be explained in terms of solid-state diffusion. Present evidence indicates the existence of a micropore system in the wustite adjacent to the magnetite with the gas/solid type of reaction occurring not only at the iron/wustite interface but also at the wustite/magnetite interface. During the partial reduction of dense hematite pellets, in a controlled atmosphere, porous magnetite and wustite are formed as products. The mean pore size, as measured by mercury injection, increases with time at constant temperature and with temperature increase over the range 6500C to 950°C. The sizes of the pores indicate that Knudsen diffusion is the principal gaseous transport mechanism across thick layers of magnetite or wustite.The kinetics of the gaseous reduction to iron are consistent with a mixed control mechanism involving the interaction of gaseous diffusion effects with a first order reversible chemical reaction at the iron/wustite interface. Because of the larger pore sizes in the iron layers, ordinary molecular gaseous diffusion must be the principal transport mechanism. The usual experimental methods used for establishing the validity of chemical rate ~ontrol are incapable of differentiating between the mixed control- mechanism and exclusive chemical control.Some implications of mixed control kinetics are developed, including a predicted independence of rate on reducing gas pressure at higher pressures.INTRODUCTIONAn extensive literature review of the reduction of iron oxides has been compiled recently by Themelis and Gauvin (1962). From the large number of papers published and the widely divergent opinions of workers in this field, it appears that a simple unified quantitative analysis of reduction kinetics is not possible. The aim of the present paper is to show that a major cause of confusion is due to the attempts of many workers to interpret experimentally observed reaction rates in terms of a single rate controlling mechanism without due regard to other rate processes which must occur simultaneously.Some of the differences in behaviour reported for particles...

Jan 1, 1964

By Alan Jessop

A small group has been set up at the Dominion Observatory, Ottawa, to make a survey of terrestrial heat flow throughout Canada. Terrestrial heat flow is the heat rising from the interior of the earth and escaping at the surface, and is calculated from a knowledge of under-ground temperature distribution and the thermal conductivity of rocks. A small number of diamond drill holes are being sunk for the purpose of measuring temperatures below the surface, but the program is inadequate for a thorough survey. Mines and holes drilled for other purposes are being sought by the Dominion Observatory group to supplement their own drilling program. F ROM January, 1.962, to December, 1964, geo-physicists of many nations will be cooperating in the "International Upper Mantle Project." Unlike tl1e International Geophysical Year, which was mainly concerned with the fluid layers surrounding the earth, the Upper Mantle Project is an intensive study of the solid earth. Canada, with its large land area and extensive Precambrian Shield, is an active participant in the project.

Jan 1, 1964

By N. A. Tiner, Saara Asunmaa

The early stages of nucleation of vacuunz-deposited gold coatings on electropolished surfaces of pure nickel and binary alloys of Ni-A1 and Ni-Ti have been studied, employing carefully controlled temperature and vacuum conditions. The preferential nucleation of gold on slip-plane edges on the crystal surfaces gave rise to a very pronounced decoration effect which was used in studying the morphology of the pain boundaries, etch pits, and slip planes on crystal faces. Characteristic surface patterns were observed with local dimensional variations. Most pronounced geometric patterns were ohserved in the pain boundaries of nickel and on the crystal faces of Ni-A1 alloy. The nucleation behauior of gold indicates contamination on the Ni-T1 alloy and the getter properties of titanium are presented as a tentative interpretation for the detected contamination. The markings and imperfections on cleavage surfaces of crystals have long been observed by optical microscopy.1,2 Surface-replica techniques are also used to detect the smallest steps and structural details on crystal surfaces by electron microscopy. Recently, Bassett3-5 and Sella, Conjeaud, and Trillat 6 have shown that, when gold is deposited onto a rocksalt cleavage surface, there is preferential nucleation at steps and slip-plane edges on the crystal surface. This gives rise to a very pronounced decoration effect which is invaluable for revealing the lattice steps on a cleavage surface. According to Bassett,3 gold atoms arriving during vacuum evaporation at the crystal surface have a certain mobility on the surface after arrival, particularly at elevated temperature. If a significant

Jan 1, 1964

By M. C. Fuerstenau

A number of interesting and. important phenomena were revealed during a study of the response of beryl to sulfonate flotation (1). Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH = 3. 0, about three ppm Fe.+++ increased recovery of leached beryl from about 60 to 100 per cent, whereas about four ppm Ca++ reduced the recovery from 60 to 2 per cent. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper "Sulfonate Flotation of Beryl", (1) even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation¬ sulfonates are precipitated immediately in solution. That is, blueish-white clouds .were noted to form after given additions of salts to. known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe (RSC3)2OH and that bonding to the surface occurs through the hydrogen of the hydroxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems lit the presence of various cations at various values of pH.

Jan 1, 1964

By R. C. Woodhead

During past years the most difficult problem presented to the coal preparation engineer has been the cleaning of fine coal, The problem of handling fine coals is more involved than the coarser sizes, because the higher surface moisture contents complicate screening, and the larger percentages of fine near size material complicate separating problems. Low gravity high capacity specific gravity separations were not possible with equipment available at that time. Coal preparation engineers did develop machines that would effect a separation of the fines, however, to maintain a high efficiency, the point of separation had to be a relatively easy one. The more difficult separations were made in the coarse coal sections of the washeries, and the fines were generally cleaned at higher specific gravities in equipment such as tables, feldspar jigs, rheolaveurs, etc. Clean products from both processes were mixed, resulting in overall lower ash contents, During the last several years, however, we have been confronted with increasing demands ZGP more precise separations of finer coals to still further reduce ash contents. A study was begun and a program instigated to improve the cleaning of fine coal, The result of this endeavor was the development of the new cycloidal heavy medium cyclone.

Jan 1, 1964

By Fred P. Giese

Southeastern reserves of titanium ores are large, widespread, and ample for anticipated demand. The leading titanium industries are mining and beneficiating sand deposits, principally in Florida, and manufacturing titanium pigments. Most of the mineral output is consumed by the producers themselves. In 1962, 20 percent of the national pigment capacity was in the Southeast.

Jan 1, 1964

By M. S. Burton, G. V. Smith, A. Rosen

The kinetics of re crystallization and the effect of recovery on recrystallization of pure iron were investigated within the temperature range of 517" to 632 OC. Grain growth and activation energies were also studied. Two stages can be distinguished during recrystallization; the first is gvowth-controlled and the second is nucleation-controlled. The extent to which the first stage succeeds before the second stage begins depends on both temperature of recrystallization and temperature of recovery. The softening of cold-worked metals and alloys due to transformation of the deformed crystals to strain-free equiaxed grains during annealing is well-known, and early inestiators established that recrystallization kinetics is strongly influenced by minute quantities of impurities. Generally, it is believed that impurities decrease the rate of recrystallization and the rate of grain growth. To understand the basic phenomena of recrystallization, investigations should be on pure materials. Most of the research on high-purity materials has been on metals having the fee Bcc materials, and especially high-purity iron, have been studied only in recent years. It is known that recovery may influence recrystalliation;" however, no general description of the influence, applicable to all materials, has been presented. This paper presents results of a study of the recrystallization kinetics of high-purity iron, after 60 pct cold deformation by drawing, with particular reference to the influence of recovery on the rates of recrystallization and grain growth. From observations of these rates, conclusions are drawn concerning nucleation. MATERIAL AND EXPERIMENTAL PROCEDURE Preparation of Material. High-purity iron, prepared by zone refining of vacuum-melted electroiytic iron at Battelle Memorial Institute under sponsorship of the American Iron and Steel Institute, was used in this study. Table I gives the reported chemical analysis of the material, taken at a point near the last molten zone and thereby rep- resenting the maximum impurity level for the entire bar. Prismatic specimens, approximately 10 x 10 X 50 mm, were sawed from the 50-mm-diam bar, perpendicular to the zone-refining direction, and turned to cylindrical shape. These specimens were sealed in quartz capsules under vacuum, approximately 10"e mm Hg, austenitized at 930° C for 15 min, slowly cooled, removed from the capsules, and cold-worked in air by swaging to approximately 20-pct reduction of area. The encapsulating, austenitizing, and swaging operations were repeated two additional times, after which the samples were encapsulated, austenitized, and cold-drawn to 60-pct reduction of area. A further vacuum anneal at 630°C for 120 min and cold drawing to 60-pct reduction of area produced wire 2.8 mm in diameter. The drawn wire was electropolished to remove deformed material on the surface, after which it was sawed into 4-mm-long specimens for the recrystallization study. Microscopical examination before the final cold reduction revealed equiaxed grain structure with very fine grains in a thin layer near the surfaces of the specimen and nearly uniform ASTM 3-4 grain size in the center. Recrystallization Heat Treatment. a) Direct Recrystallization of Cold-Worked The 60 pct cold drawn iron specimens were recrystallized at five temperatures, 517, 556, 590°, 612, and 632C, in a lead bath covered with graphite (the temperature was controlled to 1°C). Specimens were treated for twelve different times at each temperature, and all were water-quenched after heat &eatment. b) Recrystallization Following Preliminary Recovery Heat Treatment. After cold working, specimens were sealed into quartz capsules under vacuum, 105 mm Hg, and recovery-annealed at 362", 400", and 440°C for 20 hr prior to recrystallization. No evidence of recrystallization was found

Jan 1, 1964

By Charles L. Mantell, Kurt Straler

The hydrogen reduction of Cr2O3 to chromium metal was found to be feasible at very low water-vapor concentrations, corresponding to dew points of -38° to -24°C, over a temperature range of 1130" to 1490°C. Hydrogen reduction under these conditions was predicted by the calculated equilibrium curves which also indicated that CrzOs is reduced directly to chromium without forming the intermediate oxide, CrO. This reduction path was confirmed by X-ray diffraction analysis. The percent reduction of Cr2O3 at each reaction temperature was constant with time, suggesting an inhibiting effect of water vapor. A small increase in the residual water-vapor concentration of a single temperature, 1490°C, strongly retarded the rate of reduction This effect was expressed by an empim'cal equation which indicated a direct relationship between "distance from equilibrium" and the rate of reduction. me effect of temperature over the range of 1130" to 1490°C was expressed in an Arvhenius plot of log rate vs reciprocal absolute temperature. From this curve the apparent enthalpy of activation was found to be 29,600 cal. Based on the hypothesis that the rate of reductiun is contvolled at the oxide-metal interface, an over-all rate equation consistent with the experimental data and the thery of absolute reaction rates was formulated. A simplification of this expression to an Arrhenius equation was justified by the overriding effect of temperature on the rate of reaction for the minimum water-vapor concentration range. MOST of the metals in Subgroup V1 of the periodic table can be prepared commercially by direct reduction of their oxides by hydrogen or carbon monoxide, at temperatures considerably below the melting points of both the metals and their oxides. Chromium is an exception, being generally reduced from its ore, Cr2O3 . FeO, by silicon in an electric arc furnace which operates above the melting point of the Fe-Cr alloy or above the melting point of chro- mium if a chromium oxide be the starting material. In reduction of chromium oxide by hydrogen, either reduction does not occur at all or the rate of reduction is extremely slow. Theoretical considerations based on the high, exothermic, free energy of formation of Cr2O3 compared to the oxides of the other Subgroup VI metals, molybdenum, tungsten, and uranium, would also suggest a slow rate of reaction and a high activation energy. Interest in the direct gaseous reduction of fine-powdered ores in fluidized beds was considered justification for examination of this reaction. In order to develop a basis for a continuing study of the commercial feasibility of the direct gaseous reduction of chromite, a study of the kinetics of the reduction of Cr2O3 with hydrogen was undertaken. To the authors' knowledge no accurate kinetic data for this reaction have been obtained. Neither has an activation energy been determined nor has an attempt been made to establish a mechanism of reaction. LITERATURE Maier10 compared the data of I. Y. Granaat,6 H. von Wartenburg and S. Aoyama, and G. Grube and M. Flad7 with that derived from calorimetric and ther-modynamic properties for the equilibria for the reduction of Cr2O3 with hydrogen. These results, plotted as the log of the equilibrium constant vs absolute temperature for the reduction of Cr2O3 and the intermediate oxide, CrO, to chromium, show agreement between the differently derived data. In both cases the equilibrium constants were extremely low. Maier showed that, over a temperature range of 1000° to 2000°K, Cr2O3 is more readily reducible than CrO. Granat assumed that CrO was preferentially formed from Cr2o3 above 1100°C. Grube and Flad's analysis of their reaction products in the 895" to 1000°C range indicated the coexistence of only Cr2O3 and chromium. The hydrogen reduction of the other Subgroup VI metals, molybdenum, tungsten, and uranium, shows that reduction of the higher oxide proceeds through all of the intermediate oxides before being reduced to the metal. Since evidence pointed to an anomaly in the reduction behavior of Cr2O3, the authors investigated the reduction path of Cr2Os.to chromium. This was done theoretically with more recently available free-energy data and experimentally by X-ray diffraction analysis. This work reinforces Maier's conclusion.

Jan 1, 1964

By Walter Kawa

Bureau of Mines research on the hydrogenation of coal has been concerned with developing processes that could be used to supplement the Nation's petroleum and natural gas resources. Motor fuel was produced in a subsidized coal hydrogenation industry in Europe prior to 1945, but the process used is still not economical and other methods of producing liquid and gaseous fuels from coal are being investigated. As an aid to the planning of coal hydrogenation research, a literature survey was made of processes or methods of hydrogenating coal that differ from the subsidized or conventional process. This report contains a bibliography of unconventional methods of hydrogenating coal and a brief discussion of the economics of the conventional method. A general discussion of unconventional methods is included, and the advantages and disadvantages are pointed out where possible. The survey supplements a previous Bureau of Mines survey3 and a comprehensive review published in 1930.4

Jan 1, 1964

By Burke Trafton

An earlier paper1 introduced a rapid solution for mine ventilation network problems, employing the digital computer. In this paper, refinements and additions to the computer program which expand its scope of application and a solution to a ventilation network having a coal-mine configuration are presented. Specifically, the revised program--written in FORTRAN for the IBM 7074 computer in Penn State's Computation Center--is applicable to any mine ventilation network employing natural splitting and having its fan located externally. It accomplishes the following; 1. Distributes an assumed total quantity of air flow among all air- ways of the network, performing iterations until an acceptable level of error is attained and the flow in each airway is known. 2, Computes the pressure drop (head loss) in all airways and the overall network and mine head losses. 3. Determines the operating point for the mine and a given fan, adjusting all air flows and head losses to the actual values.

Jan 1, 1964

By D. L. Ritter, N. J. Grant, B. C. Giessen

Forty-six alloys covering the complete concentration range of the Nb-Rh system were examined by metallographic and X-ray methods; solubility limits of terminal ad intermediate phases and transformation and solidus temperatures were determined. There are nine intermediate phases; two eutectic, five peritectic, two eutectoid, and three peritectnid reactions were encountered. The experimental methods and the constitution diagram are described in Part I. Part 11 deals with the crys -tallography and relation of the intermediate phases. The Nb-Rh system was selected for study for three reasons: first, it was hoped that the anticipated similarity of the Nb-Rh phase diagram to the Ta-Rh1 and Ta-Ir2 diagrams treated earlier (see also Ref. 3) and to the Nb-1r4 diagram treated simultaneously would allow a crystallographic and comparative evaluation of the intermediate phases in these related systems; second, it was likely that the previous experimental methods could be carried over without significant change; and third, it was expected that the interesting mechanical properties of the a1 phase of the Ta-Rh and Ta-Ir systems would also be encountered in similar phases of the new systems, and that these phases could be investigated more closely. The phase diagram had not been treated fully in the literature; only brief surveys of some intermediate phases were found.5-7 It was attempted to cover the details of the phase boundaries, Part I, as well as to present the crystallography of the intermediate phases, Part 11. EXPERIMENTAL METHODS Specimen Preparation and Treatment. The following high-purity starting materials were used. 1) Niobium powder, 99.8 pct pure, mesh size -60 +200, from Wah Chang Corp., Albany, Ore. The analysis furnished by the supplier showed the following major impurities: Ta, <500 ppm; Zr, <500 ppm; 0, 300 ppm; Fe, 280 ppm; Ti, <I50 ppm; W, Si, <100 ppm; C, N, 30 ppm; all other impurities, <30 ppm. 2) Rhodium powder, ground sponge, 99.9+ pct pure, mesh size -80, from J. Bishop Co., Malvern,

Jan 1, 1964

By E. O. Lilge, H. Siebert

A design of a multiple-bomb leaching unit particularly suited for the study of heterogeneous reactions, i.e. sol id-liquid-gas interfaces at high temperatures and pressures is presented. The component parts and overall design are described and illustrated in detail. The system has been tested by a limited number of experiments and found to work satisfactorily. Heterogeneous reactions at solid-liquid-gas interfaces, at high temperatures and pressures, are studied in either autoclaves1&apos;4 or bombs5&apos;9. Autoclaves are usually fairly large vessels which have a stirring arrangement incorporated in the design. Mechanical design limits the use of these vessels to relatively low temperatures and pressures. They are particularly well suited to rate or kinetic studies. Bombs can be designed to be operated at high temperatures and pressures, and are smaller vessels; because of this, stirring arrangements are not easily incorporated. In this paper a multiple-bomb system is described, that has been designed to incorporate the desirable features of both the autoclave and the bomb. The described unit has flexibility for an over all study of leaching. Most of the component units in this assemblage are standard equipment, designed and produced by well known manufacturers. No claim is made to the design of this equipment, and although described in some detail, this is done merely for clarity in the elucidation of the system presented. The general layout of the multiple-bomb assemblage is shown in Fig. 1A and 1B. The basic units in this system are: 1) 6 stainless steel 100 ml bombs (Fig. 4)

Jan 1, 1964

By William A. Beck

This report describes the loading and transportation practices employed at the zinc-lead mines of The Eagle-Picher Co., Jo Daviess County, Ill., and Lafayette County, Wis. The report also gives a brief history of the Illinois-Wisconsin zinc-lead district and the operations of the company in the area. The diesel-powered, rubber-tired loading and haulage equipment is described and illustrated from the operational point of view only, and an analysis is made of the materials-handling system without going into health and safety Factors. The costs per ton of the various components of mechanical loading, underground haulage, underground crushing, and hoisting for fiscal year 1960 are tabulated.

Jan 1, 1964

By R. P. Smith

The diffusivity of carbon in iron, cobalt, and alloys of 89.7 and 79.3 wt pct Co has been determined by a decarburization method for the temperature range 850° to 1100°C. The Plots of log D us 1/T for the two Fe-Co alloys are linear through the region of the Curie temperature, showing that, unlike some cases of substitutional diffusion, carbon diffusion in these alloys is not affected by electron spin order. RECENT investigations1-&apos; have shown that for substitutional diffusion in iron the change in diffusivity with temperature does not follow an Arrhenius equation, at temperatures near the Curie temperature. Data on the diffusivity of carbon in a iron5"9 indicate that this anomaly does not exist for interstitial diffusion; however, this has not been definitely established. Since cobalt and Fe-Co alloys, 80 to 100 pct Co, have Curie temperatures in a temperature range convenient for carbon-diffusion measurements they are suitable systems for studying the relation of interstitial diffusion and the Curie temperature. EXPERIMENTAL The carbon diffusivity, D, was determined by a decarburization method. The diffusion cylinders, made from small vacuum melts of electrolytic cobalt and plastiron, were about 0.76 cm diam and 6.3 cm long. A small amount of carbon was added to each melt to keep the oxygen content as low as possible. The cylinders were first treated with a hydrogen-3 pct water vapor mixture at 1100°C to constant weight, then carburized to the desired initial carbon content with a suitable CO-C02 gas mix-

Jan 1, 1964